You can create one price list in Currency A and then a second price list for Currency B
The first price list has the actual prices, the second price list is only used to convert those prices to Currency B.
When you create the second price list:
Specify the currency on the first screen
In the lower part of the screen, click on the "All Products" line (under "Pricelist items")
Change "Based On" to "Other Price List"
Enter the name of the first price in the field "Other Price List"
Save
Now you can select this price list and it will automatically convert to the selected currency. It can have the same name as the first price list because Odoo add the currency code at the end.
You will need to have selected the more advanced pricing option ("Prices computed from formulas") and the user needs to be authorized to "Manage Pricelist Items".
Do you already have a price list in your base currency and want a foreign currency version (based on the current exchange rate)?
I want a pricelist in my base currency. Currently using USD to invoice need base currency against usd exchange rate